$def with (fool,greeting)
<!doctype html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>fool test</title>
</head>
<body>
<!-- if fool : that means if fool is NOT NULL -->

$if fool == "I am fool":
	<em style ="color:red; font-size:2em">hello wang <br/>$greeting</em>
$else:
	hello,test.
	$fool
</body>
</html>